X-ray systems are equipped with diaphragms which are used for variably restricting the x-rays to the required height and width. The undesired x-ray components are absorbed by the diaphragm blades which are normally made of lead. The diaphragms of such x-ray devices normally feature two pairs of lead blades. These pairs of blades are activated symmetrically to the center of the detector and isocentrically to the x-ray tube. The plate-type diaphragm blades cannot just be enlarged as required since this would also enlarge the aperture which for example leads to limitations in angulations on a C-arm of the x-ray device. An asymmetric display of an area under examination by means of a mechanical movement of the detector or the C-arm is known from DE 101 33 657 A1.